The present invention relates to a cross cutter for webs of material, comprising cutting means including two cutter rolls coupled together and having knives thereon and a drive having a driving motor and especially an adjustable asymmetrical mechanism (coupler mechanism) driving the cutter rolls, at the moment of the cut, in synchronism with the web of material.
In a known cross cutter of this type the asymmetrical mechanism is arranged between the driving motor and the cutter rolls and rigidly coupled with a cutter roll shaft, with the cutter rolls rigidly coupled together.
At a uniform speed of the motor, the asymmetrical mechanism has the effect that the cutter rolls are accelerated and retarded during a revolution. This control of the speed of rotation of the cutter rolls makes possible, in the case of synchronism between web of material and knives, on the one hand a shear cut and, on the other hand, the independence of the sheet length from the circumference of the cutter rolls.
Since, at a uniform speed of the driving motor, the forces for the acceleration and retardation of the cutter rolls are absorbed by the asymmetrical mechanism and because of the large mass of the cutter rolls these forces are substantial, the drive must therefore be sturdily constructed. With the complexity of an asymmetrical mechanism this means a substantial cost factor. (Jagenberg "Technische Informationen ti", III/302).